WASHINGTON
— THE Chevy Corvette ZR-1 blasts from zero to 60 miles an hour in less than five seconds. That's not all. A recent advertisement says that in one test, a modified 'Vette zoomed 5,000 miles ``at an average speed of over 175 m.p.h.!'' Speed, power, and acceleration are back in vogue in Detroit just as Congress grapples with the most difficult energy issue in years: whether automakers should be forced to manufacture fuel-efficient cars that average 40 miles per gallon by the year 2001.

Sen. Richard Bryan (D) of Nevada argues that Detroit, as well as Tokyo, must put aside their newest fascination with head-snapping horsepower, and focus on saving petroleum. It's an issue of national security, he says.

Automakers like Ronald Boltz, vice president of Chrysler Corporation, respond that America's aging population in the 1990s will prefer roomier cars, not smaller, high-mileage automobiles favored by conservationists. ``That's what our customers want,'' he says.

The issue could soon spill onto the floor of the US Senate. A bill written by Senator Bryan (S.279) now has more than 40 co-sponsors, and appears headed for easy passage; the White House threatens a veto.

In June, the National Academy of Sciences will issue a preliminary report exploring all aspects of the mileage requirement, which is commonly referred to by its acronym, CAFE, or Corporate Average Fuel Economy. NAS will study the impact of higher CAFE rules on safety, performance, and US jobs.

The current CAFE law requires that every manufacturer, foreign and domestic, sell a fleet of autos in the US which attains an average of 27.5 miles per gallon. Within each company, some cars can get less than that (such as Lincoln Town Car), and some can get more (such as Ford Escort). But the overall average must be 27.5.

Bryan's bill would require that each automaker boost its average 20 percent by 1996 and 40 percent by 2001. For most automakers, that will mean reaching 34 m.p.g. by 1996, and 40 m.p.g. by 2001.

Focusing the debate

Most of the debate in Washington has focused on the 40 m.p.g. figure, but some experts think both sides are arguing the wrong thing. Ralph Colello, vice president and managing director of Arthur D. Little Inc., in Cambridge, Mass., says that instead of arguing about mileage, the debate on the Bryan bill should be about time.

``With present technological know-how, a 40 percent improvement in fuel efficiency is possible ... without sacrificing our basic values,'' Mr. Colello says. Cars can be just as roomy and just as safe, ``but it can't be done by 2001,'' he says.

``The most significant parameter that most investigators have ignored, and I have not seen debated adequately, is the parameter of time.''

Colello was asked by the Department of Transportation to assemble a basic handbook of facts and figures to help NAS experts grapple with the CAFE issue. Colello, clutching a thick copy of his study, says it is clear that 40 mile-per-gallon cars are feasible without reducing Americans to riding to work in ``two-seater motorscooters,'' as Deputy Energy Secretary W. Henson Moore suggests.

However, Colello says it could take significantly longer than the 10 years allowed in the Bryan bill to achieve that goal, especially for US companies.

Understanding the time factor requires a little background. It also explains why the White House is concerned that the Bryan bill would cost the US many jobs.

The production cycle

US automakers normally redesign a major car model, such as the Ford Taurus, every eight years. The design process itself takes at least five years. Therefore, if Ford started redesigning its Taurus today, it would finish the redesign in 1996, and would build that new model until 2004.

Steve Plotkin, a senior associate at the Office of Technology Assessment, says: ``Many ... car models require spending $1 billion prior to the first car being rolled out of production. The automaker hopes to pay off this investment over the life of the model, which typically has averaged about eight years.''

Mr. Plotkin notes that under the Bryan bill, cars introduced in 1994 or 1995 may have to be withdrawn from production by 2001 - prior to their normal cycle. That could cost Detroit billions at a time when all three US firms are fighting foreign competition.

However, John DeCicco, research associate for the American Council for an Energy-Efficient Economy, says the Bryan bill includes protection against the Japanese for US firms.

Bryan requires 40 percent improvements for everybody. But at the moment, Japanese cars get better mileage than US cars. ``That means the Japanese have to work just as hard as the Americans,'' says Dr. DeCicco. Indeed, some Japanese companies might have to push their average mileage up toward 45 m.p.g. to meet Bryan's requirements.

But there is another problem: Japanese car companies use only a four-year product cycle. A new Honda Civic introduced today would only be on the market four years; then it would be replaced with a totally redesigned Civic in just 48 months.

The Japanese process is ``just a lot more productive than ours,'' says Colello, who has also served as a consultant to US auto firms.

Why are American companies so slow? ``The American car companies got caught,'' Colello says. ``We had enjoyed the superior position for so long.''

American companies are scrambling to speed their design process. At least one automaker, General Motors's Saturn division, says it already can update its products as frequently as the Japanese.

DeCicco admits the Japanese have a design advantage over most US automakers. But he says: ``American companies have to get on the ball. We can't sacrifice national security and the environment because their manufacturing and management systems are antiquated.''